Today, quick disconnect couplings are widely used to connect and disconnect hoses and other types of fluid conduits. One particularly advantageous type of coupling uses a male coupling member having an annular groove adjacent its connecting terminus. The male coupling member is received by and selectively coupled to a female coupling member that includes a pair of oppositely disposed pivotally mounted cam arms. The cam arms are manually movable between an unlocked position, in which the arms extend radially outwardly from the female coupling member, to a lock position, in which the cam arms are positioned alongside of the female coupling member. The cam arms include cam surfaces which are configured such that the radial extension of the cam surfaces vary in accordance with the position of the cam arms. When the cam arms are in an unlocked position, the cam surfaces do not extend fully into the groove of the male coupling member, and the male coupling member is axially movable out of the female coupling member. When the cam arms are in the lock position, the cam surfaces extend fully into and are pressed against the annular groove of the male coupling member, thereby securing the male and female coupling members in interlocking relationship.
Unless the cam arms are adequately prevented from rotation, there is a risk that they can be inadvertently rotated. Inadvertent rotation of the cam arms will uncouple the male coupling member from the female coupling member. Thus it has been found desirable to provide mechanisms for preventing such inadvertent rotation. One such mechanism, widely used today, is exemplified in U.S. Pat. Nos. 5,295,717 and 5,435,604. This mechanism includes a reciprocally movable plunger disposed in each of the cam arms. The plunger is spring biased to an extended position. When in this extended position, an inboard end of the plunger passes through a complimentary shaped hole in a retaining seat of the female coupling member, thereby preventing relative rotation between the cam arm and the female coupling member. The outboard end of the plunger is attached to a pull ring. Pulling of the ring overcomes the bias of the plunger spring and retracts the plunger into the cam arm. When the plunger is retracted, rotational movement of the cam arm to the unlocked position is permitted. Upon rotating the cam arm from the unlocked position to the locked position, an inclined surface at the tip of the plunger abuts a distal surface of the retaining seat in order to guide the plunger into the complementary shaped hole.
While plunger type locking mechanisms successfully prevent the inadvertent rotation of cam arms, they still have a number of shortcomings. One significant shortcoming relates to maintenance of these locking mechanisms. Because quick disconnect couplings are typically used at or near gasoline filling stations, they are frequently exposed to dirt, fuel, and grease. These elements easily become lodged in the interior recesses of the coupling member, including the passageway that houses the plunger. When this passageway becomes exposed to dirt and other debris, the movement of the plunger can be impeded and, thus, the device can fail to lock the cam arms. Moreover, it is often difficult to remove dirt and debris from the passageway because of its small size and because other parts of the coupling, including the plunger itself, obstruct access to the passageway.
In addition to being difficult to clean and maintain, plunger type mechanisms make the disconnection of the coupling members more time consuming and difficult. To unlock the coupling members when a plunger type locking mechanism is employed, the ring attached to the plunger must first be pulled in a direction parallel with the longitudinal axis of the coupling. The pulling of the ring overcomes the bias of the plunger spring and removes the plunger from the complimentary shaped hole. When plunger is clear of the hole, the cam arms can then be rotated radially outwardly from the female coupling member. Once the cam arms are rotated to their unlocked position, the coupling members can be disconnected. Thus, two movements are required to unlock the coupling members: one movement substantially parallel to the axis of the coupling members (for removing the plunger), and one movement substantially perpendicular to the axis of the coupling members (for rotating the cam arms). These two movements are more time consuming and difficult to perform than a single continuous movement.
In addition, plunger type locking mechanisms may also require the user to utilize two hands to unlock one cam arm: one hand to steady the coupling and the other hand to pull the plunger and then rotate the cam arm. Thus, only one such mechanism could be unlocked at a time by the user, making the process of unlocking two cam arms (the number typically used with quick disconnect couplings) more time consuming and difficult. A more efficient design would permit the unlocking of both cam arms simultaneously.
Moreover, plunger type locking mechanisms can fail when the pull ring is removed or damaged. The pull ring prevents rotation of the plunger about its axis, thereby preventing the inclined surface of the plunger from being misplaced relative to the distal surface of the retaining seat when the cam arm is being pivoted to the locked position. If the pull ring is damaged or removed, the plunger may rotate about its axis, causing the inclined surface to become misaligned from the distal surface and preventing the plunger from being guided into the complementary shaped hole. This misalignment can result in the failure of the locking mechanism as well as damage to the coupling and/or the mechanism itself.
Accordingly, to overcome the above and other problems, it is desirable to have a lock mechanism for limiting the rotation of a cam arm which is easy to clean and maintain. Furthermore, it is desirable to have such a mechanism that permits the unlocking of a cam arm by a single continuous movement from the user. It is also desirable to have such a mechanism that allows both cam arms to be unlocked simultaneously. Moreover, a lock mechanism that functions without the presence of a pull ring is desired.